I didnt mention the extent of what I know about this becuase I didn't feel the need, but being its pressing on this topic, my local gun dealer down the road from my house was a partner with my Father. He and Pop went around CONUS selling for H&K. There are only a few 'dealer samples' on the market that are 'factory' MP5's and even those began life as SA's. 99% of what you will find on the transferable market are infact conversions either registered as SEAR/SEAR PACK/REG. RECEIVER.

You cant argue with the horses mouth, bud. But this is a trivial argument and you can beleive what you want. I've given you the right information. You do with it as you will.

BTW. The MP5 is a 3 pin swingdown as well (I grew up with one). The trigger packs can switch between platforms. Dad used to switch them between the 53 he had made (I think John Flemming did it... but dont really remember), his G3 (factory), and his factory MP5K-PDW & SD dealer samples. The two pin your thinking of is called "Clipped and Pinned" lower.